Refining process



May-29, 1945.

N. F. LINYN REFINING PROCESS DML MLNHIYIURN $4 v QQ 3N wlw kwik D mw ms S hij-Zay u uwzuqfou Patented May 29, 1945 UNITED STATES PATENT FFICE REFINING PROCESS Norman F. Linn, Roselle Park, N. J., assignor, by

mesne assignments, to Standard Catalytic Company, a corporation of Delaware Application February 10, 1942, Serial No. 430,176

(ci. 19e-'49) Claims.

'I'he present invention relates to improvements in the art of producing motor fuels and in particular, it relates to a combined and continuous process which utilizes the advantages of uidized powdered catalyst for the hydroformlng of naphthas and for the dehydrogenation of light hydrocarbon gases evolved in the hydroforming process.

It is generally known that hydrocarbons boiling substantially within the gasoline range may be improved as to quality, particularly as regards octane number, by subjecting them to what is known as a hydroforming operation, that is to say, to a treatment carried out at elevated temperatures in the presence of hydrogen and a suitable catalyst at elevated temperatures.

It is further known that in the hydroforming process certain gases are formed and in stabilizing the hydroformed product these gases may be recovered separately from the Ahydroformed naphtha or the like. If, for example, butadiene is desired, the overhead product from the stabilizer may be further fractionated to obtain a C4 fraction which fraction may be subjected to dehydrogenating conditions.

Both the reforming and the dehydrogenation may be carried out in the presence` of added hydrogen from a common feed line.

One object of my invention is to carry out a combined process in which I hydroform a naphtha or gasoline and in which I also dehydrogenate the C4 hydrocarbons which are formed in the hydroforming operation to `recover olefins or diolens such as butadiene. y

A further object of my invention is to hydroform a naphtha and to dehydrogenate selected fractions of the lighter hydrocarbon gases produced in the hydroforming process by a common udized catalyst which when deactivated is regenerated in a common regeneration vessel and then recycled.

A more specific object of my invention is to reform naphtha or gasoline ina continuous operation in the presence of a powdered hydroforming catalyst, such as molybdena or chromia on a support comprising aluminum oxide or magnesium oxide, or a mixture of aluminum oxide and magnesium oxide.

My invention will be best understood by the recitation of a preferred modication thereof in the form of a specific example, and I shall now set forth such an example with the understanding that the precise details I am about to specify are purely illustrative and are not limitative.

A better understanding of my invention may be had by 4reference to the accompanying drawing which indicates a flow plan in which my F. whereupon the oil is withdrawn through line 4 and thence discharged into an upow reactor 6. This reactor carries a grid 8 located in the bottom portion thereof but spaced apart from the actual base a relatively short distance. Hydrogen is discharged through line 44 into a furnace coil 46 and then through lines 48 and 50 into the bottom of the said reactor. The amount of hydrogen fed into the reactor may vary from 10 to mol per cent of the naphtha feed. The catalyst may be fed into the reactor at a point above the grid by any convenient means as by, for example, a screw conveyor indicated simply by line I0. The hydrocarbon vapors pass upwardly through the reactor at such a linear velocity that the catalyst which may, for example. be chromia admixed with alumina in such proportion that the mixture contains 20 to 30% by weight of chromia, the balance being alumina, and which catalyst has a particle size of from 200 to 400 mesh that a dense suspension of catalyst is maintained within the reactor up to a point indicated by L in the drawing. The density of this suspension from the grid to the level L may be from 5 to 40 lbs./cu. ft. This condition may be maintained by controlling the linear velocity of the gas through the reaction zone at a volume within the limits of from 0.5 to 3.0 ft./second. Furthermore, conditions are so maintained that the hydrocarbon oil remains resident in the reactor for a period of time which may vary from a few seconds to 20 minutes. Above L in the reactor 6, the hydrocarbon vapors contain only a relatively small amount of catalyst of the order of 0.025 lb./cu. ft. or less, indicating of course that there is only a small amount of catalyst in this region.

These vapors are withdrawn from the reactor through line I2 and discharged into a cyclone separator I4 where the catalyst contained in the vapors is separated from said vapors and then is withdrawn. through -line I6 and returned through line I to the reactor. Following the vapor product, the same is withdrawn from cyclone separator |4 through line I8 and may be sent to othersolid gas separating devices, such as other cyclone separators or an electrical precipator, to remove the last traces of catalyst contained therein. 'I'hese otherseparating devices are not shown in the drawing. `In any event, the vapors are then passed through condensers 20 and thence into a separation chamber 25. The chamber operates at a temperature of about 110 F., and from this chamber water may be withdrawn from the bottom while gaseous constituents are withdrawn overhead through line 30.

The reformed naphtha is taken of! the separation chamber 25 as a side stream through line 35 and thence discharged into a stabilizer 40 which may be in the form of a fractionating column. 'Ihe gases withdrawn through line `3|) comprise hydrogen or gases rich in hydrogen, and these gases are recycled through line 42 into line 44 leading into furnace coil 46 where they are .mixed with hydrogen which may be withdrawn through any outside zones, or these gases may be passed through a scrubbing tower I2 and then recycled. Once the operation has begun, it is no longer necessary to use any extraneous hydrogen-containing gas since sufficient hydrogen is produced by dehydrogenation of the feed.

Referring back to stabilizer 40, the bottoms are withdrawn therefrom through line El) and discharged into a fractionator 52 from which the reformed gasoline may be withdrawn through line 65 while the heavy bottoms are withdrawn through line 5l. In order to carry out the distillation taking place in fractionator 52, the material may be withdrawn through line l5, passed through a reboiler i2 and returned to the iractionator through line 55.

Referring back to the reactor Ei, the same may be of the bottoms draw-o type, that is to say, catalyst may be withdrawn through outlet pipe 80 and thence discharged 1mto line S2 and thereafter into a, regenerator 85. Regenerator 85 may be of the same construction and operated in the same manner as reactor 5; that is to say, it may have a grid located at near the bottom thereof, and the catalyst which is regenerated may be withdrawn from the bottom. The catalyst may be conveyed in line 80 by means of a carrier gas, such as ilue gas or by any other convenient means adapted to convey the material into the regenerator. Preferably the catalyst leaving the reaction zone 6 through the pipe 80 may be stripped by means of steam discharged into pipe 80 through line 88. In the regenerator 85 the carbonaceous components present in the catalyst as a result of its contact with the oil in reactor 6 may be consumed by combustion by discharging air or other free oxygen-containing gas into the bottom of the regenerator through line 90. The conditions for regenerating catalyst are well known in the art and need not be repeated herein; suflice it to say that conditions are controlled in the regenerator to prevent overheating or fusing of catalyst. As previously indicated, the catalyst is maintained in a dense suspension in the regenerator up to some convenient level such as L', as was the case in reactor 6. Above the level L the ilue gas contains only a very small amount of catalyst, less than about 0.025 lb. /cu.ft. 'I'his flue gas from regeneration is withdrawn through line 92 and preferably discharged into a cyclone separator 94 where the catalyst is separated from the flue gas and the latter is vented from the system through line 86, or it may be used to strip the catalyst withdrawn from reactor 6 through line 80. Instead of usingv one cyclone, two or more may be used to insure complete removal of catalyst, or other separating devices, such as electrical precipitators, may be used for the purpose indicated.

The catalyst separated in the cyclone separator 94 and the other cyclones, if they are used, is returned to the system. As indicated, the regenerated catalyst is Withdrawn through line H62 from regenerator 85, and this catalyst may be conveyed by line |05 into line 56 where it mixes with the hydrogen previously referred to and returns to the hydroforming reactor. Alternatively, however, the catalyst or at least a portion thereof is used in a dehydrogenation step subsequently to be described.

With respect to the dehydrogenation step, one source of the gases to be dehydrogenated may be those withdrawn overhead from stabilizer 4B through line I0. These gases by the modication shown in the drawing are discharged into a scrubber ||2 into the top of which through line Ml a heavy naphtha or some other solvent may be discharged. The naphtha serves to remove from the gasin line IU at least a portion of the hydrocarbon gases and the undissolved hydrogen may be recovered overhead through line HG and returned to line 42 for reuse in the process, as previously described. The fat oil containing the dissolved hydrocarbons is withdrawn from the scrubber H2 through line M8, thence passed through a heat exchanger H20 and thence discharged into a stripper l2? where the iat oil at a temperature of about F., more or less, is stripped of its hydrocarbon material dissolved therein in scrubber H2 and the thus stripped oil, commonly called lean oil, is recycled through line il@ to scrubber H2. The hydrocarbon material stripped from the fat oil is withdrawn through line |25 and discharged into a fractionator ll. From fractionator |21, as shown in the drawing, the product charged thereto is divided into three fractions as follows: a heavy cut boiling within the gasoline range is withdrawn from the fractionator through line |35 and discharged into line 35 leading into stabilizer 40; a light fraction containing hydrogen and hydrocarbons lighter than a C4z cut are withdrawn from the fractionator through line |32, thence discharged through line |33 into line ||5 for recycling through line 42 tofurnace coil 46 for reuse in the process taking place in reactor 6.

The main product, that is to say, the C4 cut is taken o fractionator |27 through line Mtl, and this cut contains a mixture of saturated and unsaturated C4 hydrocarbons primarily. This cut is discharged into a scrubber M5 Where it is treated with an adsorbent such as aqueous ammonia introduced into the top of the scrubber through line |48. This aqueous ammonia dissolves out of the C4 cut preferentially the unsaturated-hydrocarbons such as the butenes and the butadienes, and the fat liquor containing these unsaturates is withdrawn through line |46 and discharged into a stripper |5| after passage through a heater |50 disposed in line |69. In the stripper the unsaturates are volatilized oi from the adsorbent liquid and withdrawn overhead through line |53. The lean adsorbent is withdrawn from the bottom of the stripper through liine |48 and returned to the scrubber |45 for reuse in the process. The saturated C4 hydrocarbons are withdrawn from the absorber through pipe |56 and thence discharged into a heater |58 and thence discharged into the bottom of a dehydrogenation reactor |60. Catalyst is withdrawn from line through lines tot, |30 and discharged into the dehydrogenation reactor |60. The reactor i60 is of the same construction as hydroormer 5 and regenerator 85, that is to say, it -Wan elongated vertical vessel having a grid located in the lower portion thereof through which the Ci hydrocarbons are discharged into the dehydrogenator and where they form with the catalyst a dense fluidized mass and further wherein the catalyst is drawn oil from the bottom of the dehydrogenator.

The temperature conditions maintained within the dehydrogenator vary from 950 to 1150 F.;

the dense phase suspension of catalyst in the f gases has a density of from 5 to 30 lbs/cu. ft.; the gas velocity varies from 0.5 to 3 .it/sec.; a pressure of from -10 to 5 lbs/Sq. in. gauge is maintained in the dehydrogenator; and a contact time of from 1 to 50 seconds represents the range of residence time of the CA. hydrocarbons in the dehydrogenator to effect satisfactory re suits.

As indicated, the catalyst is continuously withdrawn from the dehydrogenator through drawoff pipe |68, and this catalyst may be mixed with a carrier gas such as steam and discharged into spent catalyst line 82 for recycling to regenerator 85. The dehydrogenated products are withdrawn from dehydrogenator |60 through line ll7 and discharged into a cyclone separator tttwhere entrained catalyst may be separated and returned through line |10 to the regenerator. The concentration o catalyst in separator |60 is very low, namely, of the order of 0.025 lb./cu. ft. Usually one cyclone separator or the equivalent thereof is suilicient to completely separate the catalyst from the reaction products. However, additional separating equipment may be used.

The gases containing saturated and unsaturated hydrocarbons are Withdrawn overhead from cyclone separator |59 through line and discharged into fractionator |21,

Referring again to stripper |5|, the unsaturated hydrocarbons are withdrawn, as indicated, through line |53, passedthrough a furnace |80 and thence discharged into a second dehydrogenation vessel |85, of the same construction as dehydrogenator |60. The butene stream is diluted with from 1 to 10 volumes of an inert gas such as Iiue gas, CO2, N2, H2O, etc., per volume of butene. Catalyst is supplied to this dehydrogenator through lines |65 and |00. The overhead product from dehydrogenator |05 is withdrawn through line |90 and thence discharged into a cyclone separator |92 where entrained catalyst may be separated, withdrawn through linea H5, |99, lSl-a and |91 and passed to the dehydrogenator |60. Or, the catalyst in line |95 may be passed through lines |90, |90, and 02 to regenerator 8E. A carrier gas such as steam is used to fluidize the catalyst.

The bult; of the catalyst in dehydrogenator is withdrawn through line ISS-a, thence discharged into line Isl and thereafter discharged into dehydrogenator |60. Alternately, the catalyst in line ISG- a may be passed to regenerator 85 via lines |86 and 82. Also, the catalyst in line lat from both dehydrogenators |60 and |85 may be discharged directly through line la in to |00 and thereafter into reformerA 6. The advantage of this modification of my invention is that I use the hot catalyst from the dehydrogenators to supply heat to reformer 6,which latter operates at a much lower temperature than the said reactors |60 and |85, the catalyst issuing from the last-named reactors being at the product which contains mono-folelns, diolen' ns and hydrogen is discharged into a separator 200 and from this separator a desired product, namely, butadiene is recovered through line 2|0. The bottoms containing mono-olefins are withdrawn through line 2|2 and recycled to dehydrogenator |80. It should -be pointed out that the separation' in vessel 200 may be effected by extraction, distillation or any other convenient method. In the dehydrogenation operations tal:- ing place in reactors |85 and |60 hydrogen is preferably present, although other diluents, such as flue gas, nitrogen, steam, carbon dioxide, or mixtures thereof may be used instead.

Having described one method of operating my process, I wish to point out that the essential features of the invention reside in carrying out a hydroforming operation in connection with a dehydrogenation operation employing the same catalyst in both operations and employing also a common regenerator where the catalyst fouled in the dehydrogenation or the reforming operation may be reviviie'd. The modification which I have shown in the drawing employs the so called fluid catalyst technique, that is to say, a continuous operation in which the catalyst is in the form of a fluent stream of powder. In the below tabulation, I have set forth operating conditions which give good results:

Ste tion by causing water gas reaction. l

1 (a) Broad range, Si) preferred range.

Catalysis include e oxides or sul'lides of metals ofthe IV, such as alumina, alumina gels, magnesio, or natural or activated am or inert gas asa diluent in B or C-5-10 mois of steam per mol hydrocarbon aids in removing coke from catalyst during dehydrogena- V, VI, and VIII groups used alone, in combination or supported on carriers clays. These carriers may be treated with hydroiluorlc acid or iluosillclc acid What I claim is:

1. In the combined process of reforming naphtha and dehydrogenating C4 hydrocarbons formed during the reforming step, the improvement which comprises heating the naphtha to reforming temperatures, suspending a powdered catalyst therez'n, adding hydrogen to form a dense uidized mass of catalyst in hydrogen gas and naphtha vapors, subjecting the naphtha to reforming in` the presence of the hydrogen and uidized catalyst, separatingl catalyst from the reformedl products, recovering C4 hydrocarbons from said reformed products, heating the said C4 hydrocarbons to dehydrogenation temperatures, suspending the same kind of catalyst in the said heated C4 hydrocarbons, subjecting the C4 hydrocarbons to dehydrogenat-ion in the presence of a fluidized mass of catalyst, separating the catalyst from the products of dehydrogenation, combining a portion of the catalyst thus removed from the dehydrogenationproducts with the catalyst separated from the reformed products, regenerating the mixture in the same regenerator and passing the remaining portion of the dehydrogenation catalyst while still hot directly to the reforming reaction.

2. In a combined continuous catalytic naphtha reforming and normally gaseous paraffin dehydrogenation process wherein the said normally gaseous parafiins are produced during the said reforming, the improvement which comprises carrying out the reforming and the dehydrogenation reactions in the presence of a powdered catalyst present as a dense uidized mass in the reactant vapors and gases, respectively, separating the catalyst from the products of each reaction, regeneratingthe catalyst recovered from the naphtha reforming operation, employing the catalyst thus regenerated as the catalyst for the dehydrogenation reaction and introducing the hot catalyst recovered from the dehydrogenation directly into the reforming operation.

3. In the combined process of catalytically reforming naphtha in the vapor phase in the presence of a powdered catalyst and hydrogen and catalytically dehydrogenating C4 hydrocarbons in two separate stages and in the presence of the same kind" of catalyst employed in the reforming operation, the catalyst being present as a dense fiuidized mass in the said C4 hydrocarbons during the dehydrogenation reaction, the improvement comprising employing regenerated catalyst in the dehydrogenation operations and employing catalyst recovered substantially uncooled and unregenerated from the dehydrogenation operations in the reforming reaction,

4. The method set forth in claim 3 in which extraneous hydrogen is added during the dehydrogenation reactions.

5. The method set forth in claim 3 in which catalyst is recovered from a second stage of the dehydrogenation and passed directly to a rst dehydrogenation stage.

NORMAN F. LINN. 

